What is this – and why do you care?

As a glass manufacturer, Viridian publishes performance data based on… well, the glass (i.e. 'centre-of-glass' values). But as we know, the frame you put around the glass makes a big difference to the overall window performance (the ‘whole-of-window’ performance data) – the figure you need for your Section J calculation. And we know that, as designers, it can be really frustrating to try to find a window suite of a certain performance, which has the glass you want.

…until now.

To help you assess the glazing options available, we’ve prepared some new tables. In a friendly and familiar format, we show estimates of how a broad range of Viridian glass products perform in a set of industry-typical frames: a ready reckoner for frame and glass combinations that give you a "sensible first estimate" for progressing your façade calculations for provisional design.

As you finalise your design, use this data to assist your search of the WERS database for an equivalent window. If the window you seek doesn't already exist in WERS, then armed with these ballpark figures from our new tables, you can confidently request your chosen combination to be modelled by your preferred fabricator.

Complete your details

To access your Window Performance Data Estimation Tool (PDF), submit your details below, ensuring you include a valid email address so we can send you information about updates to the data.

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How to use the tool

1. Determine

Determine your facade performance specification and aesthetic requirements (visible light transmission, U-value, SHGC, and any aesthetic factors like colour, translucency, etc.)

2. Select

Select a generic frame format you'd like to examine. E.g. 100mm standard aluminium fixed window.

3. Search

Search down the table for glass types that meet your specification in that frame. Prepare your provisional energy calculations with this estimate data.

4. Prepare

As the design progresses and you go to prepare your Section J assessment, find a fabricator/ system offering your combination of frame type and glass within the WERS database.

If your preferred window supplier does not have your chosen glass type rated in their frame, request a new rating to be prepared by your fabricator. This is a quite straightforward process, which your fabricator can arrange for you.